Phosphosulfurized hydrocarbon polymer stabilized with 2,5-bis(alkyldithio)-1,3,4-thiadiazole

ABSTRACT

OLEAGINOUS CRANKCASE LUBRICANTS CONTAINING PHOSPHOSULFURIZED HYDROCARBON POLYMER RESIST DETERIORATION DURING INSERVICE USE FOR INTERNAL COMBUSTION ENGINE LUBRICATION BUT THE PUNGENT, OBNOXIOUS ODOR AND CONTINUAL HYDROGEN SULFIDE EVOLUTION CHARACTERISTTIC OF SUCH PHOSPHOSULFURIZED HYDROCARBON DURING SUCH USE HAVE PREVENTED USE OF SAID OLEAGINOUS CRANKCASE LUBRICANTS. SAID ODOR AND INSTABILITY OF SUCH PHOSPHOSULFURIZED HYDROCARBON ARE IMPROVED BY ADDING THERETO A MINOR AMOUNT OF 2,5-BIS(ALKYLTHIO)-1,3,4THIADIAZOLE AND THE RESULTING COMPOSITION PROVIDES INHIBITION TO BEARING METAL CORROSION AND OXIDATIVE THICKENING OF OLEAGINOUS CRANKCASE LUBRICANTS.

United States Patent PHosPnosULFURIzEI) iIYnRocARBoN POLY- MER STABILIZED wrrn 2,5-BlS(ALKYLDITHIO)- 1,3,4-TH1ADIAZOLE John H. Udelhofen, Wheaton, Roger W. Watson, Batavia,

and Adam S. Kurasiewicz, Wheaton, Ill., assignors to Standard Oil Company, Chicago, Ill. No Drawing. Filed Oct. 13, 1972, Ser. No. 297,379 Int. Cl. C07g 17/00 US. Cl 260-139 9 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF INVENTION Phosphosulfurized hydrocarbon polymers of number average molecular weight (H,,) in the range of 150 to 50,000 derived by reaction of said hydrocarbon polymer and a phosphorus sulfide, preferably phosphorus pentasulfide, and the use of such phosphosulfurized hydrocarbon in oleaginous lubricants to inhibit their deterioration have been known since the issuance of US. Pat. No. 2,316,079 on Apr. 6, 1943, to Clarence M. Loane and James W. Gaynor. According to that patent, whose disclosure is incorporated by reference and made a part hereof, such phosphosulfurized hydrocarbons are prepared by reaction of a 150-50,000 fi polymer of low molecular weight monoolefin; e.g. propene, isobutylene or mixtures of isobutylene with butene-l and butene-Z, with a phosphorus sulfide, preferably P 8 in an amount from 5 to 25 percent by weight of the polymer at a temperature in the range of 93 to 232 C.

However, the commercial use of such phosphosulfurized hydrocarbons as addition agents for oleaginous crankcase lubricants was not, in general, accepted because such phosphosulfurized hydrocarbons characteristically had a pungent, obnoxious odor and a storage instability, and continual H 8 liberation which was more pronounced during use of the crankcase lubricant. Such H S release also cause corrosion of lead and/ or copper-containing bearings.

The pending federally imposed limitation on emissions from internal combustion engines and the attendant severity of performance of oleaginous crankcase lubricants for such engines have strongly indicated the need for a substantially ashless crankcase oleaginous lubricant formulation. While detergent-dispersant addition agents of the ashless type, such as high molecular weight succinimides and amides and high molecular weight Mannich reaction products from alkylphenol, amine and formaldehyde, have been developed and commercially used in oleaginous crankcase lubricants, non-metallic inhibitors of bearing metal corrosion and oxidative thickening of the base oleaginous lubricant are just presently being investigated for use under such impending severe service conditions.

SUMMARY OF THE INVENTION It has been discovered that quite unexpectedly the addition of a minor amount of 2,5-bis(alkyldithio)-l,3,4-thiadiazole to the phosphosulfurized hydrocarbon polymer of 3,826,798 Patented July 30, 1974 the aforementioned Loane and Gaynor patent suppresses the characteristic pungent, obnoxious odor and continual H 5 release of such phosphosulfurized hydrocarbon polymer. Such suppression of odor and instability by the bis- (alkyldithio)thiadiazole is unexpected because of its sulfur content which might be expected at least to accentuate the odor problem. The resulting combination of such phosphosulfurized hydrocarbon polymer and minor amount, generally in the range of 0.1 to 50 weight percent of 2,5- bis(alkyldithio)-1,3,4-thiadiazole can be used as an addition agent for oleaginous based lubricants to lubricate internal combustion gasoline and diesel engines of 4 and 2 stroke cycles employing crankcase lubrication or lubrication by addition of lubricants to the engines fuel as is common in 2 stroke gasoline engines. Such use of the combination of such phosphosulfurized hydrocarbon polymer and minor amount of the bis(alkyldithio)thiadiazole provides an ashless-type inhibitor for bearing metal, especially Pb, Cu and Pb-Cu bearings, corrosion and for oxidative thickening of oleaginous base lubricants.

The 2,5-bis(alkyldithio)-l,3,4-thiadiazoles and their preparation have been known from the teachings, respectively, in US. Pats. No. 2,719,126 and No. 3,087,932. Said bis(alkyldithio)thiadiazoles can have alkyl-substitucuts of from 1-280 carbon atoms and can be prepared by oxidative coupling of 2,5-dimercapto-1,3,4-thiadiazole with a C to C alkylhydrocarbon mercaptan in the respective reactant molar ratio of 1:2. For a more complete understanding of the 2,5-bis(alkyldithio)-l,3,4-thiadiazoles of the teachings of the above two patents are incorporated herein by reference.

SPECIFIC EMBODIMENTS To improve the odor and storage as well as use stability of the aforementioned phosphosulfurized hydrocarbon polymer of the Loane and Gaynor patent, it is preferred to use a minor amount, less than 50 weight percent but within the range of 0.1 to 50 weight percent, of 2,5-bis(alkyldithio)-1,3,5-thiadiazole wherein the alkyl group contains at least 8 carbon atoms. Such preference 1s a practical one and is based on the solubility in oleaginous lubricants of the bis(alkyldithio)thiadiazoles in said concentrations. The bis(alkyldithio)thiadiazoles having smaller alkyl groups, i.e. less than about 8 do not have sufficient solubility in oleaginous lubricants to make practical use of them even though they do have the ability to improve the odor and stability of the phosphosulfurized hydrocarbon polymers. Preferably the concentration of the preferred bis(alkyldithio)thiadiazole is 1 to 25 weight percent of the phosphosulfurized hydrocarbon polymer and such preference is based on the need for practical inhibition of bearing metal corrosion and oxidative thickening of the oleaginous base lubricant.

The foregoing combination of phosphosulfurized hydrocarbon and l-25 weight percent thereof of the preferred 2,5-bis(alkyldithi0)-1,3,4-thiadiazole can be used as addition agent in oleaginous lubricants in concentrations of from 0.01 to 20 percent by volume (the combination is fluid) but preferably in concentrations of 0.1 to 10 volume percent based on practical needs for inhibiting bearing metal corrosion and oxidative thickening of oleaginous base lubricants. Said compositions of phosphosulfurized' hydrocarbon polymer and 1-25 weight percent bis- (alkyldithio)thiadiazole are useful in transmission and industrial lubricants where oxidative stability of the lubricants where oxidative stability of the lubricant is necessary.

Preferred for the present invention is the phosphosulfurized hydrocarbon polymer of the Loane and Gaynor patent which is derived from polypropene or polybutene polymers of 200 to 4000 M and 5 to 25 weight percent thereon of P 8 reacted at a temperature of -205 C.

TAB LE I [Phosphosulfurized polypropene and polybutene polymers] Percent P285 on Polymer used (Mn) polymer S:P ratio 11 1. 44 o l1 1. 65 Polybutene (320) 26 1. 53 Polypropene (800)- 11 1. 23 o ll 1. 53 Polggiropene (575)-..- 16 1. 38 o 27 1. 43

The following examples illustrate the benefits to be obtained by this invention and how to practice it.

EXAMPLE 1 A mixture of phosphosulfurized polybutene hydrocarbon polymer (polymer fi of 900) having the S:P ratio of 1.65: 1.0 and 25 weight percent thereof of 2,5-bis(octylditho)-1,3,4-thiadiazole is prepared. The characteristic pungent, obnoxious odor of said phosphosulfurized polybutene substantially disappeared. After storage of said mixture for seven days, it was noted that the pungent, obnoxious odor was still absent, a small amount of precipitate had appeared and no H 5 (readily detectable in very low concentration) was detected. The precipitate was likely a reaction product of some H S (precursor and the bis(alkyldithio)thiadiazole because untreated phosphosulfurized polybutene hydrocarbon stored for seven days did not have any precipitate but did retain not only the pungent, obnoxious odor and did liberate some H S.

To demonstrate inhibition of H 8 liberation from phos phosulfurized polypropene or polybutene hydrocarbon polymers, the following tests were conducted.

EXAMPLES 2-5 TABLE II Corrosion of Cu-Strip After 16 Hours Exposure to Vapors Above Phosphosulfurized Polypropene of 1.53:1.0

2,5-bis (octyldithio)-1,3,4- ASTM D130 thiadiazole, weight percent: rating (Control) 2C 2 (Example 2) 2B 3 (Example 3) 1B 4 (Example 4) 1B 5 (Example 5) 1B The foregoing ratings demonstrate that the vapors above compositions of Examples 2-5 were less corrosive than the vapor above the Control untreated phosphosulfurized polypropene. The pungent, obnoxious odor was absent from compositions of Examples 25 but present from the Control composition.

The following examples illustrate the corrosion inhibition of the present inventive compositions used as addition agents in oleaginous base lubricant.

.4 EXAMPLES 6-10 In oleaginous base oil (SAE-30 oil) there are dissolved 4.0 percent ashless detergent-dispersant of Mannich reaction type and 1.7 weight percent of phosphosulfurized polypropene. The pungent, obnoxious odor was absent solution there is dissolved 0 (Control) to 0.1 weight percent 2,5 bis(octyldithio)-1,3,4-thiadiazole. Copper strips are immersed in said solutions for 3 hours at C. and then rated according to ASTM D130. The results of these tests are shown in Table III below.

TABLE III Cu-strip corrosion after 16 hours emarsion In oleaginous solutions containing 4% ashless dispersant and 1.7% phosphosulfurized polypropene 2,5-bis(octyldithio)-1,3,4-thia- Percent on Example tiazole contentpoly-pro- ASTM D130 number weight percent Dene-P rating The above ratings demonstrate that the compositions of Examples 6-10 are less corrosive to the copper strips than the Control composition. The pungent, obnoxious odor was absent from compositions of Examples 6-10 but present from the Control composition.

The effectiveness of compositions of the present invention to inhibit corrosion of lead and copper-lead bearings is illustrated by the results of a bench test and a test run in an L-38 engine having a Cu-Pb bearings which is a standardized test using leaded gasoline and a SAE-30 grade oil as crankcase lubricant. In the Bench test the oleaginous lubricant (SAE-30 grade oil) has dissolved therein 4% detergent-dispersant described for Examples 6-10 and no corrosion inhibitor (Control Lubricant), or Example 11 composition: 1% by weight of phosphosulfurized polypropene (S:P of 1.53:1.0 of Table I) and 0.3% 2,5-bis(octyldithio)-1,3,4-thiadiazole (33% thereof on phosphosulfurized polypropene) or Example 12 composition: 1% phosphosulfurized polybutene (S:P of 1.5 :1.0 of Table I) and 0.3% 2,5-bis(octyldithio)-l,3,4- thiadiazole (33% thereof on phosphosulfurized polybutene). A separate weighed lead strip is immersed in each of the three compositions which are heated to 162- 163 C. for 20 hours while air at 30 ml./min. is injected into the liquid compositions. After such exposure the lead strips are washed with solvent to remove the oil, dried and reweighed to determine weight loss. The results of this bench test are shown in Table IV.

TABLE IV Lead Bearing Bench Corrosion Test Oil composition: Lead weight loss, mg.

Control Composition 515 Example 11 Composition 0 Example 12 Composition 0 EXAMPLE 13 The oleaginous crankcase lubricant formulation used in the L-38 Engine Test with new, weighed Pb-Cu bearing is an oleaginous (SAE-30 grade oil) base oil solution consisting of 7.0% detergent-dispersant described for Examples 6-10, 1.7% phosphosulfurized polypropene having S:P ratios of 1.53:1.0 of Table I and 0.3% 2,5-bis(octyldithio)-1,3,4-thiadiazole, 17.65% thereof on phosphosulfurized polypropene. At the completion of the standard run time of this test, the engine piston is inspected and rated for varnish deposit on a scale of 0-10, where O is heavy complete varnish cover and 10 is clean piston. The Pb-Cu bearing is washed with solvent to remove oil, dried and reweighed. From this L-38 Engine Test it is found that by the use of above oleaginous crankcase lubricant composition the piston varnish rating is 9.6 (96% clean) and there was a Pb-Cu bearing weight loss of only 33.6 mg. A 50 mg. weight loss is acceptable.

EXAMPLE 14 Example 1 is repeated but using weight percent 2,5- bis(dodecyldithio)-1,3,4-thiadiazole. No precipitate is noted after seven days storage (reaction product with B 8 is soluble) but again the treated phosphosulfurized hydrocarbon polymer had no pungent, obnoxious odor while the untreated phosphosulfurized hydrocarbon polymer has the characteristic pungent, obnoxious odor.

The foregoing examples and tests can be conducted with any of the other preferred phosphosulfurized polypropene or polybutene hydrocarbon polymers and other 2,5-bis (alkyldithio)-1,3,4-thiadiazole and similar improved results will be obtained.

What is claimed is:

1. The method of reducing the characteristic odor and improving the shelf life stability of phosphosulfurized hydrocarbons derived from reaction of P 8 with an alkene hydrocarbon having a molecular weight in the range of 200 to 4000, which method comprises adding to said phosphosulfurized hydrocarbon from 1.1-50 weight percent thereof of 2,5-bis(alkyldithio)-1,3,4-thiadiazole wherein the alkyl-substituent contains 1-280 carbon atoms.

2. The method of claim 1 wherein said phosphosulfurized hydrocarbon is derived from a liquid, viscous polypropene or polybutene having a number average molecular weight within the range of 200-4000.

3. The method of claim 2 wherein the phosphosulfurized polymeric hydrocarbon has a sulfur to phosphorus content in the weight ratio of 8:1 within the range of 1.0-3.0.

4. The method of claim 3 wherein the 2,5-bis(alkyldithio)-1,3,4-thiadiazole has an alkyl-substituent containing at least 8 carbon atoms.

5. The method of claim 4 wherein the alkyl-substituent is octyl.

6. The method of claim 4 wherein the alkyl-substituent is dodecyl.

7. The composition resulting from the method of claim 1.

8. The composition resulting from the method of claim 3.

9. The composition resulting from the method of claim 4.

US. Cl. X.R.

UNITED"STA'IES'PA'IENT OFFICE ChRTlP ICATE OF CORRLC HON Patent No. 3, ,79 Dated y 30, 97

n fl John H. Udelhofeh, Roger W. Watson, Adam S. Kurasiewies It is certified that: error appears in the above-identified paten't and that said Letters Patent are hereby cerrected as shown below;

Col. 2, Line 66-67 Should read: cant is necessary Col. 3, Line as ShoulQ read: dithio)- Col. Line 5 should read: poly'propene having S:P ratio of 1.53 for Table I. In this Col. Line "(1' v where should. be wherein sighed and sealed this 12th day of November 1.974;

(SEAL) 'Attest': v f

McCOY M. GIBSON JR. C.-MARSHALL DANN' Attesting Officer v Commissioner of Patents 

